Manualshelf

Reference Manual

ManualsBrandsEmerson ManualsControl ValvesEmerson Fisher easy-e EWT-C
12
CHEMICAL
For more information: www.fisher.com
Design EWT Valve with Cavitrol
®
Trim
Eliminates Cavitation
RESULTS
•Met demanding requirements in boiler feedwater service
and eliminated cavitation.
•Saved a power plant $10,000/year on valve trim-
replacement costs.
•Adding a FIELDVUE
®
digital valve controller to a
competitor’s valve in deaerator level control extended
the service life of that valve by three years.
APPLICATION
Deaerator level control
CUSTOMER
We Energies’ Valley Power Plant in Wisconsin
CHALLENGE
The Valley Power Plant, the largest co-generation facility in the USA,
has an unusual need for reliability. If a generating unit elsewhere goes
down, power can be obtained from the grid. If this plant loses its
steam system, however, the citizens of downtown Milwaukee will be
without heat.
In order to remove corrosive gases entrained in boiler feedwater, a
feedwater heater called a deaerator is incorporated into the power
cycle. The deaerator heats incoming feedwater to the saturation point
in order to reduce the solubility of any entrained gases.
Deaerator level control is a demanding control valve application.
Service conditions vary with plant load. During initial startup, the
condensate pumps operate at high pressures and minimal flows.
(Downstream pressure is low because the deaerator has not built up
any pressure.) As the unit load increases, the inlet pressure to the
valve decreases. The control valve, therefore, must handle high flows,
significant pressure drops (165 psid), and any resulting cavitation.
A Neles-Jamesbury Q-ball valve was installed in 1995 in this facility's
deaerator level control lines. For the next six years, the valve
experienced control and performance problems resulting from
damaging cavitation. (Cavitation, the formation and subsequent
collapse of vapor in liquid fluids, is a major source of valve damage and
vibration.) Because of cavitation damage, plant maintenance
personnel replaced the valve's trim at least once a year and at a cost of
about $10,000 USD.
“I called Emerson (Novaspect)
personnel on a Saturday, and
they not only called me back
but also provided exceptional,
technical support — regarding a
competitor’s valve
application.”
Todd Gordon
Instrument Technician Leader
We Energies
POWER GENERATION

Summary of content (2 pages)